4CH1/1C — November 2024 (Edexcel IGCSE Chemistry): Past Paper

The three states of matter are solid, liquid and gas.

Substances can change from one state to another. The box gives some words about changes of state. condensing cooling evaporation freezing heating melting sublimation Complete the table by giving the correct word from the box for each change of state. You may use each word once, more than once or not at all. Change of state Name of change from liquid to solid from gas to liquid from solid to gas

The diagram shows two states of matter for a substance. solid liquid gas Each circle represents an atom of the substance.

Complete the diagram by drawing six circles to represent atoms in the gas state.

Which statement is correct about this substance?

Complete the equation, by adding the state symbols, for the conversion of water into ice. H₂O( ) → H₂O( )

The table gives some information about five gases

Use gases from the table to answer these questions. You may use each gas once, more than once or not at all.

Name the gas needed for combustion.

Name the gas that is most abundant in air.

Name the gas that can bleach damp litmus paper.

Explain why hydrogen chloride is classified as a compound.

Why does chlorine have the highest boiling point of the gases in the table?

This question is about the rusting of iron.

Name the two substances needed for iron to rust. 1 2

Give the chemical name for rust.

The diagram shows two methods used to prevent iron from rusting. iron iron paint zinc Method A Method B Method A will work only if the paint coating is not scratched. Method B will work even if the zinc coating is scratched.

Explain how method A prevents iron from rusting.

Give the name of method B.

Explain how method B prevents iron from rusting even when the zinc coating is scratched.

A student does an experiment to identify the dyes in inks A, B, C, D and E. The student uses this apparatus.

• a piece of chromatography paper
• a beaker
• a solvent
• inks A, B, C, D and E

Describe how the student should set up the apparatus and do the experiment. You may use a diagram to help your answer.

The chromatogram shows the results for inks A, B, C, D and E. solvent front start line A B C D E

Explain which ink contains a dye that is insoluble in the solvent.

Explain which inks contain the same dye.

Describe how the student can use the chromatogram to determine the Rf value for the dye in ink C. You do not need to calculate the Rf value.

Hydrogen peroxide decomposes to form water and oxygen. This decomposition is shown in the equation. 2H₂O₂ → 2H₂O + O₂

Give the test for oxygen gas.

The rate of reaction is increased by adding a suitable catalyst. Describe how a catalyst increases the rate of a reaction.

A student uses this apparatus to investigate the rate of decomposition of hydrogen peroxide solution. The student adds 100 cm³ of hydrogen peroxide solution at 20 °C to the apparatus labelled A. The student records the volume of oxygen gas collected every minute for 16 minutes. The graph shows the student’s results

Name the pieces of apparatus labelled A and B. A B

Determine the volume of oxygen gas produced in the first 4 minutes. Show on the graph how you obtain your answer. volume of oxygen = cm³

Determine the rate of reaction at 8 minutes by drawing a suitable tangent to the curve. Include the units for the rate of reaction. rate of reaction = units

This question is about ionic and covalent compounds.

The table gives the formulae of some positive ions, some negative ions and some compounds containing these ions

Complete the table by giving the three missing formulae.

Give the name of the compound with the formula Al₂(SO₄)₃

The diagram shows the arrangement of electrons in an atom of magnesium and an atom of chlorine. Magnesium Chlorine Describe, in terms of electrons, what happens when magnesium atoms and chlorine atoms form magnesium chloride.

Complete the dot-and-cross diagram to show the outer shell electrons in a molecule of ammonia. N H H H

Describe the forces of attraction in a covalent bond.

Magnesium sulfate crystals have the formula MgSO4.xH2O

A student uses this apparatus to heat tube A and collect water of crystallisation in tube B.

Apparatus (printed in the paper): magnesium sulfate crystals — tube A — tube B — heat — ice water.

The student records the mass of tube B at the start and every minute for 6 minutes. The table gives the student's results.

Give a reason why the student surrounds tube B with ice.

State how the student knows when all the water of crystallisation has been given off.

Describe a chemical test the student can use to show that the liquid in tube B contains water.

The decomposition of hydrated magnesium sulfate is shown in the equation. MgSO₄.xH₂O → MgSO₄ + xH₂O At the end of the reaction, the mass of MgSO₄ remaining in the tube is 6.0 g. Use this mass and the results in the table to calculate x in MgSO₄.xH₂O [for MgSO₄ , Mr = 120 for H₂O, Mr = 18] x =

A student uses this apparatus to investigate the rate of reaction between marble chips and dilute hydrochloric acid. cotton wool dilute hydrochloric acid marble chips balance g This is the equation for the reaction. CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)

Give a reason why the reading on the balance decreases during the reaction.

Explain why the rate of reaction is greatest at the start.

After 10 minutes, the reaction stops even though there are marble chips remaining. Give a reason why the reaction stops.

The student repeats the experiment with hydrochloric acid at a higher temperature to investigate the effect on the rate of reaction.

Give two variables that should be controlled to make sure the results are valid. 1 2

Explain the effect of increasing the temperature of hydrochloric acid on the rate of reaction.

A student uses this apparatus to investigate the heat energy released when a liquid fuel burns. thermometer aluminium can water spirit burner liquid fuel This is the student’s method.

• measure the mass of the spirit burner and fuel
• add 100 g of water to the aluminium can
• measure the temperature of the water
• use the spirit burner to heat the water until the temperature rises by 50 °C
• measure the new mass of the spirit burner and fuel

Give a reason why the student uses an aluminium can rather than a glass beaker.

When the fuel burns, a black solid forms on the aluminium can.

Identify the black solid.

Give a reason why the black solid forms.

Show that the heat energy needed to raise the temperature of 100 g of water by 50 °C is approximately 20 000 J. [for water, c = 4.2 J/g/°C]

The student burns 1.84 g of ethanol. Calculate the molar enthalpy change, ΔH, in kJ/mol, for the combustion of ethanol. Include a sign in your answer. [for ethanol, Mr = 46] ΔH = kJ/mol

In a different experiment, the student burns 3.7 g of butanol. This is an equation for the incomplete combustion of butanol. C₄H₉OH(l) + O₂(g) → 2CO₂(g) + 2CO(g) + 5H₂O(g)

Complete the equation for the incomplete combustion of butanol.

Calculate the total amount, in moles, of gas produced by the incomplete combustion of 3.7 g of butanol. amount of gas = mol

This question is about alkanes and alkenes.

Ethane and ethene each react with bromine, but under different conditions.

Give a reason why ethane does not undergo an addition reaction with bromine.

Complete the equation for the substitution reaction between ethane and bromine, including an essential condition for the reaction. C₂H₆ + Br₂ → + condition

Give the colour change that occurs when ethene reacts with bromine water.

The diagram shows the displayed formulae of two compounds in the homologous series of alkenes

Compounds in the same homologous series have the same general formula. Give two other characteristics of compounds in the same homologous series. 1 2

Explain why the alkenes in the diagram are isomers.

Draw the displayed formula of another alkene that is an isomer of these two alkenes.

The reaction used to make poly(ethene) can be represented by this equation. Describe the differences between the reactant and the product in this reaction. Refer to carbon chain length, type of bond and state of matter in your answer.

This question is about the reactions of some compounds of lead.

Lead can be extracted from lead(II) sulfide, PbS, in two stages. Stage 1 lead(II) sulfide is heated in air and reacts with oxygen to produce lead(II) oxide, PbO, and sulfur dioxide Stage 2 lead(II) oxide is heated with carbon in a furnace

Write a chemical equation for the reaction in stage 1.

Give a reason why sulfur dioxide should not be released into the atmosphere.

This is the equation for stage 2. 2PbO + C → 2Pb + CO₂ A mass of 892 tonnes of lead(II) oxide is heated in a furnace with an excess of carbon. Calculate the maximum mass, in tonnes, of carbon dioxide that could be released into the atmosphere. [1 tonne = 1 × 10⁶ g] [for PbO, Mr = 223 for CO₂ , Mr = 44] mass = tonnes

The diagram shows the structures of lead(II) sulfide and sulfur dioxide. Lead(II) sulfide Sulfur dioxide Explain, in terms of bonding and structure, why lead(II) sulfide is a solid with a very high melting point at room temperature and why sulfur dioxide is a gas at room temperature. lead(II) sulfide sulfur dioxide

A different oxide of lead contains 90.7% by mass of lead and 9.3% by mass of oxygen. Determine the empirical formula of this oxide of lead. empirical formula =